Deep Tunnel, shallow thinking?

Heavy rains in April quickly swamped Chicago's underground labyrinth of sewers, forcing a stomach-churning surge of waste and runoff back into basements and flooding neighborhoods across the city.

The deluge so overloaded the city's aging infrastructure that nearly 11 billion gallons of murky, bacteria-laden wastewater were flushed into Lake Michigan, the biggest hit to Chicago's source of drinking water in nearly three decades.

With climate scientists projecting that Chicago faces more intense rainstorms in the not-so-distant future, city and regional leaders increasingly say that fixing the problem requires a new way of thinking and more spending on green projects that allow runoff to soak into the ground before it reaches sewers.

Cities from Philadelphia to Seattle already are moving aggressively to prevent basement backups and sewage overflows without the expensive work of laying pipes and boring tunnels. Milwaukee is the first city in the nation with a federal stormwater permit that legally requires "green infrastructure," such as streets and parking lots with permeable pavement and neighborhood rain gardens designed to capture the first flush of stormwater.

But beyond a few pilot projects, Chicago has been slow to follow up on a decade of promises to spread green infrastructure widely across the city.

For instance, the Green Alley program promoted by former Mayor Richard Daley has overhauled just 1 percent of the 1,900 miles of Chicago alleys with permeable pavement, according to city records. Other than a showcase project on Cermak Road in the Pilsen neighborhood, city officials could not provide details about any other street outfitted with green infrastructure.

"If we incorporated this kind of work every time we dug up a street in Chicago, it could make a big difference over time," said Hal Sprague, manager of water policy for the Center for Neighborhood Technology, a nonprofit group that has been advocating the use of green infrastructure since the 1970s.

The costs of the existing system's shortcomings are only now becoming apparent. A new analysis by the center found that, from 2007 to 2011, the federal government and private insurers paid at least $660million for residential flooding and sewage backup claims in Chicago and Cook County alone.

Some households filed more than one claim during that period, the analysis found, but the total was equivalent to 1 in 6 properties suffering water damage. Poor neighborhoods appear to have suffered the most; median household income was below the Cook County average in more than two-thirds of the ZIP codes with the most costly claims.

Daley's 2003 "Water Agenda" and 2008 "Climate Action Plan" promoted green infrastructure as a solution. Mayor Rahm Emanuel embraced the idea last year in his "Sustainable Chicago 2015" plan, which called for making the projects a routine part of the city's bricks-and-mortar budget and promised to annually convert 1.5 million square feet of impervious surfaces into areas that allow runoff to seep into the ground.

But despite the years of talk about green alternatives, the city's money and political focus largely is still on big-ticket construction projects like Emanuel's program to replace and refurbish old sewer lines, funded in part by doubling water bills for the average household by 2015.

The larger official response to flooding and sewage overflows in Chicago and suburban Cook County is the Deep Tunnel, a network of massive storm sewers and cavernous flood-control reservoirs that has been under construction since the mid-1970s. The Metropolitan Water Reclamation District, a tax-supported agency that operates independently from city government, has spent more than $3 billion on the project but isn't scheduled to complete it until at least 2029.

Despite the work already accomplished, the system is not only incapable of handling bigger storms like the April deluge, according to research conducted for city planners, but renders large swaths of Chicago vulnerable to downpours as minor as two-thirds of an inch.

"I feel over the edge and so do most of my neighbors," said Katrina Pekovic-Dobrovolny, a real estate agent whose home in the Dunning neighborhood has flooded four times during the past decade. "If we're getting these once-a-century storms every two or three years, we need to do something different. Because what we're doing now doesn't seem to work."

City officials declined repeated requests to make someone available for an interview and would only answer questions in writing. In an email, a spokesman for the Chicago Department of Water Management said ongoing sewer work will help alleviate flooding and basement backups.

This year the city plans to install 17 miles of new sewers and refurbish another 49 miles of pipes and 14,000 catch basins, according to the email. In the flood-prone Albany Park neighborhood, the city and water reclamation district are jointly funding a special tunnel intended to prevent the Chicago River from spilling over its banks.

Work continues on a yet-to-be-released plan to increase the use of green infrastructure, city officials said. For now the city is distributing rain barrels, offering discounts on trees and shrubbery and encouraging residents to disconnect their household downspouts from neighborhood sewers.

Other cities also are building and overhauling sewers. But countering what became standard policy during the last century, municipal leaders across the country have decided that building bigger pipes or digging tunnels deep underground isn't going to solve their water woes.

Philadelphia has committed to spend $2.4 billion during the next 25 years on green infrastructure. After building its own Deep Tunnel, Milwaukee is focusing on green projects in a new effort to capture a rainstorm's first half-inch and eliminate basement backups by 2035. In Seattle, Mayor Mike McGinn ordered city departments in March to dramatically increase the use of permeable pavement, rain gardens and green corridors along streets to absorb runoff.

"These things already are being done in bits and pieces around the country," said Karen Hobbs, a senior water analyst for the nonprofit Natural Resources Defense Council who formerly worked as a top official in the now-defunct Chicago Department of Environment. "But we still need to change our mindset about how we spend our limited budget for infrastructure investments."

Studies have found the projects help. In Milwaukee and Grand Rapids, Mich., for instance, green infrastructure reduced runoff by up to 3 percent in neighborhoods where public and private construction work included runoff-absorbing methods.

In Chicago, city and regional leaders say the problem starts with sewers built more than a century ago. Not only do some of them leak, the pipes were designed to combine waste from homes and factories with storm runoff. When the area is hit with heavy rains, the pipes quickly fill to capacity and a fetid mix of sewage and runoff is either forced back into basements or spilled into local waterways.

More intense storms, like the one in April when rain fell for several consecutive days, can force officials to open locks and gates to Lake Michigan.

The water reclamation district contends that Chicago and suburban Cook County will finally start seeing relief when a Deep Tunnel reservoir in south suburban Thornton is completed in 2015 and another in McCook is partially completed in 2017. The McCook reservoir won't be fully operational until 2029.

The two converted quarries will hold 18 billion gallons collected from 130 miles of tunnels, 9 to 35 feet in diameter, that are connected to smaller neighborhood sewers. Once a storm passes, the wastewater will be pumped back to sewage plants for treatment.

After years of delays, a pending legal settlement with federal and state authorities would impose court-enforced deadlines to finish the sprawling plumbing system. The deal also would require the district to start investing in green infrastructure projects that, over time, would divert at least 10 million gallons per storm, according to the U.S. Environmental Protection Agency.

Environmental groups that sued for changes contend the proposed deal doesn't go far enough. The Deep Tunnel service area encompasses 350 square miles, but the completed green projects would capture the equivalent of a half-inch of rain on just one square mile.

Meanwhile, some officials with the water district are starting to agree with other experts that the Deep Tunnel may not solve the problem even when it is finished. Officials fear that a system designed in the 1960s and '70s won't be able to handle a projected increase in big storms where rain falls hard and fast.

"It's hard to handle that amount of water," said David St. Pierre, the district's executive director. "Regardless of what (Deep Tunnel) is doing, it won't necessarily mitigate basement backups. If we don't get a cultural change about how we look at water, we aren't going to solve this problem."

In his first budget address to lawmakers, Democratic Gov. Tom Wolf laid out an ambitious $33.8 billion spending plan that raises taxes a combined 16 percent while slashing corporate and property taxes, restores cuts to education and wipes out the state's deficit.